The purpose of this project is to identify modifiable maternal exposures in early pregnancy that may increase the risk for having a pregnancy affected by certain major, structural birth defects. Grantees will use data from existing birth defects surveillance systems to identify children with the 17 birth defects categories. Mothers of these case infants and mothers of randomly selected live born control infants will be contacted and invited to participate in a maternal interview. The interview will focus on the key areas of: () diabetes, obesity, and physical activity; (2) other chronic maternal medical conditions; (3) infertility; and (4) medication use; in addition to other exposures with promising prevention potential such as genitourinary infections, fever, and maternal occupation. Kits will be mailed to participating families to collect saliva samples and provisions will be made for the collection of residual newborn bloodspots, enhancing the potential for gene-environment interaction studies.